The overall aim of this project is to investigate the effects of major dietary components on chylomicron-triglyceride fatty acid (TGFA) metabolism in rats. Within the framework of this broad objective the investigators expect to: 1. Examine the rate of removal of chylomicron-TGFA from the plasma of rats fed a diet high in fat (polyunsaturated fatty acids) or high in carbohydrate (sucrose, fructose, or starch). These studies will extend those reported by Harris and Felts (1973) in which a difference was observed between rats fed diets high in glucose and those fed diets high in saturated fat. 2. Correlate tissue lipoprotein lipase (LPL) activity in rats fed the experimental diets described above with the rate of removal of chylomicron-TGFA. These studies will extend those of Weisenberg-DeLorme and Harris (1975), who found a direct correlation between skeletal muscle LPL and chylomicron-TGFA clearance in the diets used by Harris and Felts (1973). 3. Correlate plasma insulin and glucagon with tissue LPL activity in the animals fed the experimental diets. 4. Characterize the effect of the experimental diets on the apolipoproteins of the plasma lipoproteins with special attention to the Apo C and Apo E proteins, which have regulatory effects on LPL. It is hoped that the information gained by this study will contribute to a more complete understanding of the factors regulating chylomicron-TGFA removal from the circulation and of the role of diet in the utilization of dietary fat. In addition, it may contribute to our understanding of the defects in triglyceride metabolism in diabetes and lead to further studies in this area.